My immediate thought is that the certificates weree not correctly recovered as part of the recovery process. To check run the "bptestbpcd -verbose -client <client>" from the master and verify that the client's certificates match that of the master server.
If it does not - review the nbhostidentity command to import the DR package again.
As rightly pointed by @davidmoline either you missed to import DR package or it didnt happend correctly. Shutdown NetBackup Services and try importing DR package
nbhostidentity.exe -import -infile F:\my_DR_files\HotCat_1538592193_FULL.drpkg
Don't remember the passphrase . However we have two DR sites and AIR is configured for backup images & Catalog replication. So we have two NetBackup at two different DR sites. Can we get the passphrase from any NetBackup which are on DR sites ?
The passphrase is not stored anywhere in NBU in clear text.
It is up to the backup admin to make a note and store it in a safe place.
As per Admin Guide I:
Caution: If you fail to provide the appropriate passphrase while you install
NetBackup on the master server after a disaster, you may need to redeploy
the security certificates on all NetBackup hosts. For more details, refer to the
if you do not remember "exactly" the passphrase there is a command to test it. If you are lucky, you may guess it
nbhostidentity -testpassphrase -infile <DR_file>
If someone else put the passphrase for you and you can not find it, you have to recreate the whole certificate "structure" from the scratch.
If you still have the old master server available, you may be able to reset the DR passphrase and run a new catalog backup. You can then you the new DR package to recover the certificates.
If the old master is gone, then unless you can find someone who knows the passphrase you have some work to generate all the certificates again.